|Publication number||US7180439 B1|
|Application number||US 11/378,543|
|Publication date||Feb 20, 2007|
|Filing date||Mar 16, 2006|
|Priority date||Mar 16, 2006|
|Also published as||WO2007108974A2, WO2007108974A3, WO2007108974B1|
|Publication number||11378543, 378543, US 7180439 B1, US 7180439B1, US-B1-7180439, US7180439 B1, US7180439B1|
|Original Assignee||Analog Devices, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Non-Patent Citations (2), Referenced by (23), Classifications (8), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
This invention relates to power supply controllers, and particularly to digital power supply controllers.
2. Description of the Related Art
Power supplies typically comprise a power stage and a controller, with the controller arranged to operate the power stage as needed to produce a desired output voltage. A power stage can be, for example, a pass transistor (for a linear power supply) or a switching circuit which drives an output inductor and capacitor (for a switching power supply).
A typical switching power supply which includes an analog controller is shown in
One possible digital controller is shown in
Another approach is shown in
A digital power supply controller is presented which overcomes the problems noted above, providing digital control of reference voltage and filtering without the need for a high-bandwidth/high-resolution ADC or a high-resolution DAC.
The present digital power supply controller is referred to as a ‘multi-path’ controller, in that the high frequency and low frequency components of Vout are processed with separate ADCs. A first ADC (ADC1) is coupled to Vout and is arranged to provide a digital output which varies with the low frequency components of Vout, and a second ADC (ADC2) is coupled to Vout and arranged to provide a digital output which varies with Vout's high frequency components. A digital reference value is subtracted from the digital output of ADC1 to produce a low frequency digital error signal, and a summing circuit sums the low frequency digital error signal and the digital output of ADC2. Processing circuitry is arranged to produce an output which varies with the summed signal and is suitable for coupling to a power stage for use in regulating Vout.
When so arranged, ADC1 can be a low-bandwidth high-resolution ADC and ADC2 can be a high-bandwidth low-resolution ADC, both of which are low-cost components. A high pass filter (HPF) would typically be connected between Vout and the input of ADC2 to ensure that only the high frequency components of Vout are presented to the high-bandwidth low-resolution ADC2.
The processing circuitry, which typically includes a digital filter, forms part of the power supply's control loop, and can be adapted for use with a number of power supply types, including those employing resonant and linear topologies.
Further features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings.
The basic principles of a power supply controller in accordance with the present invention are illustrated in
Conventionally, providing a digital controller capable of accommodating the high-frequency and low-frequency components of Vout requires the use of an ADC which meets the requirements imposed by both frequency components. A high-resolution/high-bandwidth ADC of this sort may be unacceptably costly. The invention overcomes this problem by employing two ADCs: a first ADC (ADC1) having characteristics suitable for converting the low-frequency components of Vout, and a second ADC (ADC2) suitable for converting Vout's high-frequency components. This is preferably accomplished by arranging the ADCs such that, relative to each other, ADC1 is a low-bandwidth high-resolution ADC and ADC2 is a high-bandwidth low-resolution ADC. By so doing, both ADCs can be relatively low-priced devices in comparison with the high-bandwidth high-resolution ADC that might otherwise be required. Note that, as noted above, typically only a fraction of Vout is fed back to the ADCsamplifier4, via a voltage divider (not shown for simplicity).
The present controller also includes a means 52, typically a digital subtraction circuit, for subtracting a digital reference value (Vref) from the digital output 53 of ADC1 to produce a low frequency digital error signal 54. Digital reference value Vref would typically represent a desired value for power supply output voltage Vout. A summing circuit 56 sums low frequency digital error signal 54 and the digital output 57 of ADC2, producing summed signal 58. Summed signal 58 is provided to processing circuitry 60, which is arranged to produce an output 62 which varies with summed signal 58 and is suitable for coupling to power stage 50 for use in regulating Vout. The present controller can be designed to implement one of several different power supply types, including switching, resonant, and linear topologies.
One possible implementation of a multi-path power supply controller in accordance with the present invention is shown in
ADC1 is preferably arranged to perform a low-pass filter function on Vout. To that end, ADC1 is preferably an oversampling converter such as a sigma delta (SD) converter. An SD converter consists of an SD modulator and a decimation filter, which functions as a digital low-pass filter. This arrangement provides a low-cost, low-bandwidth, high-resolution ADC.
For this configuration, the DC accuracy of the control loop is determined by ADC1, and the DC gain of ADC2 is essentially zero. Since there is no DC accuracy requirement for HPF 70 to meet, it can be implemented very inexpensively.
The present controller can be employed in a number of different power supply types, including various switching and linear topologies. A typical switching power supply will have a power stage 50 such as that shown in
The present controller might also be employed in a power supply having a resonant topology; this is depicted in
As noted above, the present controller might also be employed in a linear power supply; this is depicted in
Also note that, though not shown, a controller per the present invention might receive multiple control signals that are combined with summed signal 58 to perform various functions. Possible control signals could be associated, for example, with soft-start and soft-stop routines and current sharing functions. During start-up, a limiting control signal might be added to reduce in-rush current or output voltage overshoot. For current sharing, an offset signal might be added to match the output currents of multiple parallel power supplies. Limiters, such as a PWM limit circuit, might also be used to avoid breakdown of external power components.
Note that the power supply configurations shown in
While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.
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|U.S. Classification||341/155, 341/144, 341/141|
|Cooperative Classification||H02M3/157, H02M7/529|
|European Classification||H02M7/529, H02M3/157|
|Mar 16, 2006||AS||Assignment|
Owner name: ANALOG DEVICES, INC., MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BAKKER, ANTHONIUS;REEL/FRAME:017654/0737
Effective date: 20060313
|Aug 20, 2010||FPAY||Fee payment|
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|Jul 23, 2014||FPAY||Fee payment|
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